When replacing an air conditioner or having one installed in a new home you need to consider several things. Price is the first thing most people think of but you should also think of "the long term cost to run this air conditioner while keeping your home at a comfortable temperature", the size of the air conditioner (cooling
power - tonnage), warranties and even how it is installed.
Many people try to save money by having a smaller (cheaper) air conditioner installed. What they don't realize is that on a hot day in Florida that it could take this air condition could take hours to bring the the air down to a comfortable temperature. In fact, if the air conditioner is too small it may never be able to bring the air down to what you consider a low temperature. Also,
running a small air conditioner at low temperatures can cause the unit to "freeze up" which can cause severe damage to the unit. And worse when you call for a warranty repair they A/C company may tell you that the damages are going to be at your expense because the warranty states that this A/C unit is not warrantied to run below 75 degrees Fahrenheit (or something similar).
You also need to consider the energy efficiency (seer rating) of the unit. Using the wrong A/C unit can cost you thousands of dollars a year in excess electrical charges.